TYPO3 Core

There seems to be some major issue when the select box for columns is render while having backend layout setup. Columns that are not assigned a column number (and thus cannot be used as in Page module) are getting listed as available options.

See "Steps To Reproduce" to see the setup, rendered output and expected correct output.

Column configuration:
backend_layout {
colCount = 2
rowCount = 5
rows {
1 {
columns {
1 {
name =
}
2 {
name = B
colPos = 10
}
}
}
2 {
columns {
1 {
name = C
colspan = 2
colPos = 11
}
}
}
3 {
columns {
1 {
name = D
colspan = 2
}
}
}
4 {
columns {
1 {
name = E
colspan = 2
colPos = 12
}
}
}
5 {
columns {
1 {
name =
}
2 {
name = G
colPos = 13
}
}
}
}
}

Select box options when editing content:
<option value=""></option>
<option value="10">B</option>
<option value="11">C</option>
<option value="">D</option>
<option value="12" selected="selected">E</option>
<option value=""></option>
<option value="13">G</option>

Expected select box options:
<option value=""></option>
<option value="10">B</option>
<option value="11">C</option>
<option value="12" selected="selected">E</option>
<option value="13">G</option>

(issue imported from #M17745)